Up and Down Wall Street

One Born Every Minute

As exchange-traded funds pour into the market, more of them are of dubious value. Consider the Bitcoin ETF.

"There's an app for that" is the mantra behind the boom in smartphones, turning them from things used just to make calls and send texts, to devices that put mobile computing in the palm of your hand or your pocket (well, almost, as screens steadily expand in size). Financial markets have seen a parallel phenomenon: "There's an ETF for that," for all manner of things. And, as with smartphone apps, a few exchange-traded funds dominate the market, alongside thousands of dubious offerings.